1. Statement of the Technical Field
The invention relates to the field of communications. More particularly, this invention relates to an antenna assembly for a portable communications device.
2. Background of the Invention
Portable hand-held radio communication devices are often limited with regard to their long range communications capabilities. This limitation is generally attributable to the relatively low effective radiated power (ERP) associated with such radios. The relatively low ERP is due primarily to the relatively low power output of the radio frequency (RF) amplifiers used in such radios, and the poor efficiency of the antennas. For example, many of these handheld radios have conventionally been equipped with a short flexible antenna sometimes referred to as a “rubber duck” antenna or “whip” antenna. These antennas are essentially shortened vertical monopole antennas which have been electrically loaded so as to reduce their overall physical length. While such antennas are convenient, their performance is often limited by their small size and the absence of an effective counterpoise.
U.S. Pat. No. 6,940,462 to Packer (hereinafter “Packer”) discloses a body-worn antenna which overcomes many of the limitations associated with shortened, electrically loaded vertical monopole designs. In particular, Packer teaches a broadband dipole antenna that is removably fastened to a garment of the user. The antenna assembly is coupled to a portable handheld radio which is also carried by the user. The body-worn dipole design of the antenna disclosed by Packer provides higher gain and improved efficiency as compared to conventional vertical monopole designs. These improvements are attributable to the electrically balanced design of the dipole and larger physical size of the antenna.
Still, there remains a continuing need for antenna systems that offer improved performance. In particular, there is a continuing need for antennas that provide higher gain and wider operating bands. These capabilities can enable small portable hand-held radios to provide equal or better range performance compared to larger man-pack radios which are conventionally carried in a ruck-sack.